Photo-assisted electrolysis

ABSTRACT

An apparatus and method for performing electrolysis on materials such as water, thereby electrically separating the electrolyte into its elemental components. More specifically, according to a preferred aspect of the instant invention, there is provided an apparatus for splitting water into hydrogen and oxygen that uses a specially prepared cathode in conjunction with incident light energy to increase the efficiency of that process. A preferred embodiment of this apparatus uses the photo collector/cathode which comprises a thin layer of metal, preferably nickel, deposited by electroplating or a similar technique onto a conductive surface (e.g., a sheet of copper metal). During the electrolysis process, the cathode is irradiated with light, thereby reducing the amount of electrical energy necessary to separate a given quantity of electrolytic material.

[0001] This application claims the benefit of serial number 60/179,241,filed Jan. 31, 2000.

TECHNICAL FIELD

[0002] The present invention relates generally to the field ofelectrolysis and, more particularly, to the separation of water into itselemental components via electrical current.

BACKGROUND

[0003] Our world has been running on fossil fuels (coal and petroleum)for over two hundred years, and is fast using these fuels up. Since ittakes millions of years for these fuels to form, the need for analternate source of energy is growing more and more urgent. The burningof fossil fuels has also been a major contributor to pollution and apossible cause of global warming.

[0004] Wind, water, geothermal and tidal energy sources have all beendeveloped but they are limited to specific places. Fission has beendeveloped as well, but has met sturdy resistance from environmentalaction groups. Fusion energy has yet to live up to its promise. Solarenergy via photovoltaic cells has also been developed but these use lessthan 15% of the available energy and are not yet cost efficient.

[0005] Fuel cells, which produce energy by recombining oxygen andhydrogen to generate electricity, have reached 70 to 80 percentefficiency and, since they produce only water, are non-polluting and donot contribute to the greenhouse effect. Until now, the main source ofhydrogen for such systems has been through the electrolysis of water.Because energy is required for the electrolysis process, and because inany system some energy is lost to entropy, this process has beeninefficient. Many elaborate methods have been designed to reduce theamount of energy needed to split water. Because these either have notworked, or have been very expensive or inefficient processes, it has notbeen practical to scale up any of these methods for commercial use.

[0006] It has been known for over 100 years that hydrogen and oxygen gasmay be generated by the electrolysis of water. Electrolysis utilizeselectrical power to create a current between an anode and cathode,thereby breaking water into its constituent components, hydrogen andoxygen. Of course, this process has the potential to be particularlyimportant in view of the concern associated with access to hydrocarbonsin politically unstable countries. As is well known to those skilled inthe art, hydrogen is a clean, plentiful and readily usable fuel.Needless to say, an efficient and economical method of producinghydrogen from readily available materials such as water could havesignificant value, especially in countries that have few hydrocarbondeposits. Consequently, there is a growing interest in developing newtechniques for the efficient production of molecular hydrogen.

[0007] In order to reduce the amount of electrical energy necessary tosunder the hydrogen-oxygen bond in water, solar energy is being exploredas an energy source. One approach which has been actively exploredinvolves chemical processes which resemble photosynthesis in order toconvert water and air into combustible hydrocarbons. Another approach,which is the approach taken by the instant invention, is to accomplishproduction of hydrogen gas by using sunlight to effect electrolysis ofwater. Generally, the emphasis with electrolysis has been to use sometype of exotic solid state photoelectric cell to generate current andrelease hydrogen and oxygen. To date, the solid state photoelectricapproaches have not proven economically successful.

[0008] In 1905, Albert Einstein explained the photoelectric effect usingthe quantum hypothesis. The photoelectric effect involves the ejectionof electrons from a metal surface by light in a vacuum tube. Einsteindeveloped the equation for the energy of these electrons in 1906. Theequation is:

E=hν−W

[0009] This equation means that the energy (E) of the electrons is equalto Plank's constant (h), multiplied by the frequency of the light (ν),minus the work function (W) of the metal.

[0010] For the energy of the electrons to equal that needed for theelectrolysis of water, the frequency of light must be in the range ofhigh frequency ultraviolet. Thus, solar energy has heretofore had onlylimited use in producing hydrogen.

[0011] Thus, there exists a need for a method and apparatus thatprovides efficient electrolysis of water into its constituent elements.Accordingly, it should now be recognized, as was recognized by thepresent inventors, that there exists, and has existed for some time, avery real need for an invention that would address and solve theabove-described problems.

[0012] Before proceeding to a description of the present invention,however, it should be noted and remembered that the description of theinvention which follows, together with the accompanying drawings, shouldnot be construed as limiting the invention to the examples (or preferredembodiments) shown and described. This is so because those skilled inthe art to which the invention pertains will be able to devise otherforms of this invention within the ambit of the appended claims.

SUMMARY OF THE INVENTION

[0013] This instant invention provides an efficient method of performingelectrolysis on water, thereby separating it into its elementalcomponents. More specifically, according to a preferred aspect of theinstant invention, there is provided an apparatus and method forsplitting water into hydrogen and oxygen. The inventive apparatus andmethod employ a specially prepared cathode in conjunction with incidentlight energy to increase the efficiency of that process.

[0014] According to a first preferred embodiment, there is provided anelectrolysis apparatus wherein the cathode serves both as a photoncollector and as an electrode for electrolysis. Of particular importancefor purposes of the instant invention is the fact that the photoncollector/cathode consists of a thin layer of metal, preferably nickel,deposited by electroplating or some similar technique (e.g., vapordeposition) onto a conductive surface (e.g., a sheet of copper metal).The electroplating produces a “blacked” (i.e., black or nearly black orotherwise darkened) surface which appears to be a microcrystallinedeposit of metal. This metal “black” serves both to collect and absorbthe light and simultaneously acts as a cathodic surface for theelectrolysis of water. The material and structure (i.e., the way thatthe surface metal is deposited) affect the efficiency of thephoto-assisted electrolysis and operate to capture energy over a muchlarger portion of the solar spectrum.

[0015] In operation, the anode and specially prepared cathode arepreferably immersed in a solution comprising an electrolyte along withthe material (e.g., water, acetic acid, or other organic or inorganiccompound) that is to be electrolyzed. An electrical potential is thencreated between the anode and the specially prepared cathode, and thecathode is irradiated with light. Light incident upon the cathodecontributes additional energy to the electrolysis process, therebyreducing the amount of electricity necessary to separate a givenquantity of water molecules. Of course, in the preferred embodiment, theincident light will be solar light, although many other light sourcesmight be used. However, solar light sources have the advantage ofproviding photons to the reaction at no “cost”, in contrast toartificial light sources which must be supplied with power, therebyreducing the overall efficiency of the process.

[0016] Although light has previously been used to assist in theelectrolysis process, such prior usage has occurred within much morecomplex systems of semiconductors and/or metal ions complexed in organiccompounds. Thus, the principle advantage of the instant apparatus andmethod is that the inventive system operates simply and efficiently toreduce the electrical energy required for electrolysis.

[0017] Since much less energy is needed to produce hydrogen using theinventive system, fuels cells can now be run on hydrogen gas (H₂) thatis produced much efficiently and cost effectively, thus providingcommercial viability. In addition, the inventive method of producinghydrogen gas does not threaten the environment as do fossil and nuclearenergy sources.

[0018] The inventive system can be employed at any level or scale, fromindividual cell phones to power plants. Because the process usesinexpensive, readily available materials, it could be used in thirdworld countries, as well as in the earth's most technologically advancedcountries.

[0019] Furthermore, because energy and water are the only products ofthis process, the problem of pollution has been eliminated.

[0020] In addition to hydrogen production, the inventive apparatus andmethod can also be used in other electrochemical processes. For example,certain organic acids have been shown to decarbonylate and break downunder certain electrolysis conditions to methane, ethane and carbondioxide. This invention can be used to remove or reduce such acids inwaste streams through solar assisted electrolysis. A number of similarelectrochemical reactions where this invention could be used are knownin both organic and inorganic chemistry.

[0021] The foregoing has outlined in broad terms the more importantfeatures of the invention disclosed herein so that the detaileddescription that follows may be more clearly understood, and so that thecontribution of the instant inventors to the art may be betterappreciated. The instant invention is not to be limited in itsapplication to the details of the construction and to the arrangementsof the components set forth in the following description or illustratedin the drawings. Rather, the invention is capable of other embodimentsand of being practiced and carried out in various other ways notspecifically enumerated herein. Finally, it should be understood thatthe phraseology and terminology employed herein are for the purpose ofdescription and should not be regarded as limiting, unless thespecification specifically so limits the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 illustrates an end-view of a preferred electroplatingapparatus.

[0023]FIG. 2 illustrates a side-view of a the electroplating apparatusof FIG. 1.

[0024]FIG. 3 provides a side-view of inventive apparatus 40.

[0025]FIG. 4 provides a front view of inventive apparatus 40.

[0026]FIG. 5 provides a schematic diagram of an embodiment 20 of theinventive electrolysis apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] It should be noted at the outset, that within certain broad,general guidelines, the specific details of the geometry andconstruction of the inventive photo-assisted electrolysis cell are notcritical. Indeed, it is well within the ability of one of ordinary skillin the art to construct many different variations of the preferredembodiments given herein. For example, modifications may be made toenhance separation and collection of hydrogen gas and oxygen gas, reduceovervoltage requirements, enhance light collection capabilities, changethe ionic composition of the electrolytic solution, etc., withoutaltering the fundamental nature of the invention.

[0028] An example of an electroplating bath 1 of a type preferred foruse in the present invention is depicted in FIGS. 1 and 2. In theelectroplating apparatus 1, 2 is a cathode which is being blacked foruse in the inventive electrolysis processes. In this example, the basecomponent of cathode 2 is preferably a half cylinder of conductive metal(e.g., copper metal foil) 2 soldered to a wire 4 connecting it to the DCpower supply 6. Element 8 is the electroplating anode (in thisparticular example a nickel coin, i.e., a disk of nickel-containingmetal). Anode 8 is preferably moved back and forth over the innersurface of the cathode to deliver a roughly equivalent (i.e., even)layer of the electroplating metal to all parts of the inner surface ofthe cathode. Container 1 is an electroplating bath containing a solutionof a salt of the metal to be deposited on the surface of the cathode. Inthis example, the salt would preferably be NiSO₄.

[0029] In this embodiment of the inventive system, cathode 2 ispreferably a flexible sheet of metal (e.g., thin, copper metal) formedinto a half cylinder. The radius of this partial cylinder is notcritical within broad practical limits. The half cylinder 2 ispreferably attached to an insulated, conductive wire 4 by, for example,soldering, and then cleaned to remove surface contamination. The halfcylinder 2 is then preferably placed in electroplating bath 1 (e.g., asolution of nickel (II) sulfate dissolved in water) and connected toelectrical power source 6 so that it operates as the cathode in theelectroplating system 1. Anode 8 is also connected to power source 6, bymeans of insulated wire 10, to begin electro-deposition of a layer ofconductive metal (e.g., nickel) onto the concave inside surface 27 ofthe half cylinder 2.

[0030] As will be understood by those skilled in the art, other physicaland chemical approaches to depositing the active surface on cathode 2are certainly possible and have been specifically contemplated by theinstant inventors. The resulting cathode surface should be dark inappearance (rather than having a shiny metallic surface) due to itscoating by the reduced metal. As described by some chemists and as usedherein and in the claims, this sort of dark surface is referred to as a“black”. Although not essential to the invention, it is our belief thatthis black is a micro-crystalline deposit of the metal in question. The“black” layer will preferably be essentially free of any semiconductormaterials and most preferably will consist of conductive metal inelemental form. That being said, it should be noted that the instantinvention will operate, albeit not as efficiently, if the “blackened”surface is shiny.

[0031] In addition to copper, examples of other materials suitable forforming the underlying base of cathode 2 include: nickel, lead, tin,chromium, graphite or graphitic carbon, gold, silver, chromium,platinum, palladium, and alloys thereof. The base could be even formedof a plastic or other non-conductive material onto which a conductivesurface is applied, for example, by sputtering, painting, or otherprocesses. The base will preferably be essentially free of anysemiconductive materials and will most preferably consist essentially ofconductive metal in elemental form, the most important property of thebase being that it is conductive on the surface that is to form thecathode and sufficiently solid to support the coating(s). Further, it ispossible in some cases for the base to also function as the blackeningmaterial, e.g., when the base is graphite or graphite carbon.

[0032] As will also be apparent to those skilled in the art,electroplating (blacking) metals other than nickel can alternatively beemployed in the present invention. By using platinum salts and aplatinum anode, for example, a thin surface layer of “platinum black”can be obtained. Examples of other suitable blacking materials include:palladium, copper, silver, gold, zinc, cadmium, thallium, indium,gallium, lead, tin, bismuth, antimony, arsenic, tellurium, selenium,iridium, rhodium, cobalt, iron, ruthenium, osmium, rhenium, manganese,tungsten, molybdenum, chromium, tantalium, niobium, vanadium, titanium,zirconium, lanthanum, ytterbium, scandium, strontium, praseodymium,neodymium, promethium, samarium, europium, gadolinium, terbium,dysprosium, holmium, erbium, thulium, and lutetium. Examples ofadditional suitable materials include mixtures, alloys, mercuryamalgams, and combinations of the foregoing and similar metals, orcombinations of these elements with other elements, where the aboveelements constitute the major (by weight) components.

[0033] The thickness of the “black” deposit is not critical so long asit is thick enough to coat the surface of the cathode and provide a highsurface area for hydrogen generation and be dark enough to absorb lightefficiently. Nickel, platinum, and palladium are good choices forelectroplating as they are known to interact with hydrogen at an atomiclevel and are used for hydrogenerations in organic chemistry. Cobalt isalso particularly well suited for use in the inventive apparatus as thecathode plating/blacking metal.

[0034] The instant inventors have determined that, if the coating is toothick, it may potentially interfere with the electrical conductivity ofthe cathode. Thus, for purposes of the overall efficiency of the instantinvention, the preferred electrode deposit thickness will be under 1 mmthick, preferably less than 0.1 mm, and in some cases can be as littleas only a few atoms thick. If the coating is too thick, the conductivitymay suffer. If too thin, light absorption may suffer.

[0035] After a suitable amount of metal is deposited on the cathode 2,it is preferably removed from the plating bath, rinsed with water and isready to be placed in the electrolysis cell.

[0036] An embodiment 20 of the inventive electrolysis apparatus isdepicted in FIG. 5. Inventive apparatus 20 comprises: an upper valve 22;a barrel 24 (e.g., a barrel of a glass syringe); a cathode A preferablyprepared as discussed hereinabove and most preferably comprising copperfoil with nickel metal electroplated on inside surface 27 thereof; ananode 28 (e.g., a nickel-chromium wire);

[0037] an upper gas collection space 30 in barrel 24 (wherein both H2and O2 accumulate); a level 32 of electrolyte solution in barrel 24; alight source 34; a base container 36 (e.g., a beaker); and a level 38 ofelectrolyte solution in base container 36. Inside surface 27 of cathode26 preferably faces anode 28 and light source 34.

[0038] In embodiment 20 of the inventive apparatus, the anode 28 ispreferably a conductive wire composed of nickel-chromium alloy (e.g.,nichrome). However, all that is necessary is that the anode be a goodconductor of electricity and resistant to the corrosive conditions ofthe anode region of the cell. Examples of other suitable anode materialsinclude: platinum, gold, titanium, nickel, graphite or graphite carbon,and alloys thereof. The anode will preferably be essentially free of anysemiconductor materials.

[0039] Although many other arrangements are possible, the anode wire 28is preferably placed adjacent the center of half cylinder cathode Aalong the longitudinal axis thereof so that all points on the insidesurface 27 of the cathode 2 are approximately equidistant from the anode28. The half cylinder cathode 2 is preferably co-axial with the cylinderof barrel 24 and the anode 28 preferably extends along the center of thebarrel at least as far as the cathode cylinder 2 extends. Cathode 2 andanode 28 can be kept in place and alignment, for example, by placing acork or other inert structure in at the bottom of the barrel 24 whichwill hold the electrodes in place yet allow free movement ofwater/electrolyte into and out of the bottom of the syringe.

[0040] To prepare inventive electrolysis apparatus 20 for operation,valve 22 is opened and the barrel 24 is lowered into the electrolytesolution so that the solution 38 fills the bottom portion of the barrelup to the level in the surrounding container 36. Alternatively, and asfurther examples may be used to enable outside air to push theelectrolyte liquid/solution up into the cell. Then, the valve 22 isclosed and the barrel 24 is raised to a point where the bottom of thebarrel 24 is just below the surface of the solution 38 in base container36. This traps a column of the solution in barrel 24 up to level 32.This makes it possible to measure the amount of gas evolved by notingthe change in level 32 in the barrel 24. Subsequently, barrel 24 can bere-lowered into the container 36 of solution and the valve 22 opened torelease the gasses produced. Then, the valve 22 is closed, the cell 24raised, and the system is ready for further operation.

[0041] An alternative embodiment 40 of the inventive electrolysisapparatus is depicted in FIGS. 3 and 4. Inventive apparatus 40comprises: an array of anode rods (e.g., wires) 42; a sheet of blackedcathodic material 48; a preferably transparent barrier membrane 44,positioned between anode array 42 and the blacked surface of cathode 48,which will allow free flow of ions, but not bubbles 46 of H2 gas; and atransparent window 50 that allows light, preferably visible andultraviolet, to pass therethrough to the blacked surface of cathode 48.The upper portion 52 of barrier 44 is preferably impermeable to gas tomaintain separation between the hydrogen and oxygen produced.

[0042] For simplicity, the external electrical components of inventiveapparatus 40 are not shown in FIGS. 4 and 5. Window 50 can be formed ofglass. However, because much solar energy comes in the form ofultraviolet light which is largely absorbed by glass, it is preferredthat the light admitting portions of the inventive cell be constructedof quartz, polymers, or other materials which will facilitate thetransmission of UV light into the interior of the cell.

[0043] In the embodiment 20 of the inventive electrolysis apparatusdepicted in FIG. 3, no effort is made to separate the hydrogen andoxygen gasses produced. However, it should be clear that cell 20 couldbe modified to allow for separation of the gasses produced. For example,a permeable or semi-permeable membrane, or even a thin, fine mesh sheetwhich could trap bubbles, but let light and the solution pass-through,could be used.

[0044] The electrolyte solution 38 employed in the inventiveelectrolysis system is most preferably a dilute solution of sulfuricacid (H₂SO₄) in water at a pH in the range of from about 0.5 to about 7.The solution 38 will most preferably have a pH of about 2. Of course,other inorganic and organic acids may be equally useful, as would manyneutral salt solutions such as solutions of sodium sulfate (Na₂SO₄).Some salts such as sodium chloride may be less useful because of thegeneration of other gasses in the system that might be corrosive to theelectrodes. Further, some magnesium or aluminum salts can form gelsunder certain conditions of pH, which would render the cell lessconductive, less efficient, and perhaps even opaque (i.e., therebyblocking access of light to the cathode). Under some circumstances,alkaline electrolyte solutions (i.e. above pH 7) may be preferable. Themain requirements are that the solutions be relatively conductive andnot be overly corrosive to the electrodes under the electrolysisconditions, or opaque to light.

[0045] Examples of suitable electrolytes include: lithium, sodium,potassium, magnesium or beryllium, salts, specifically, sulfates,hydroxides, or fluorides, the main requirement being that theelectrolyte solution be conductive, have only limited, and preferablyno, absorbence of the incident light, and not interfere with thephoto-assisted electrochemistry occurring at the electrodes.

[0046] Current for both the electroplating and the photo-assistedelectrolysis is preferably provided by a standard commercial transformer6, 55 of the type sold as a battery replacement. This could be replacedby batteries or almost any other source of DC current. For test anddevelopment purposes it is convenient to be able to vary the current andvoltage. However, once an optimum is determined for a given cell,geometry and construction capability to vary the current should not beessential, but could be useful. For testing, it may also be desirable touse a standard meter to measure the voltages, current flow or amperage,and/or resistance of the cell or whole system, at various points before,during and after the experiment.

[0047] An overarching goal of this instant invention is to use solarenergy—especially visible and ultraviolet light—to assist in theelectrolysis of water. For testing purposes, the instant inventors haveused a common “high intensity” table lamp generally availablecommercially, although many other light sources could have been selectedin the alternative. It should be noted that this source is relativelypoor in high energy UV light and rich in lower energy visible lightphotons.

[0048] One of the distinguishing characteristics of this invention isthe ability to use visible light efficiently. If desired, filters couldbe used in to modify the light striking the cathode surface, or lensesor mirrors could be used to concentrate, reflect, or direct the light tooptimum impact on the cathode. Further, where it would be advantageousto do so, narrow band or monochromatic light sources could be used.

EXAMPLE

[0049] Using an electroplating apparatus 1 as depicted in FIGS. 1 and 2,a cathode 2 was formed and electroplated with nickel. The DC powersupply employed in the experimental system included a plug-intransformer and a variable resistor. A 5¢ nickel coin was used as theelectroplating anode 8. The anode 8 and cathode 2 were connected to thepower source using insulated copper wires 4 and 10 and alligator clips.Cathode 2 was formed from copper foil shaped as a half cylinder having adiameter substantially equal to that of a syringe barrel 24 to be usedin the next stage of the test. The bath 5 employed in the electroplatingprocess comprised one-half teaspoon NiCl₂ per 30 ml of water. Thetransformer was set at 4.5 V 300 m A and the nickel coin was moved backand forth over the inside surface of the copper cathode until the insidesurface was fully and evenly electroplated with a micro-crystallinenickel layer. At the completion of the electroplating process, thecathode 2 was removed and rinsed with tap water.

[0050] Next, cathode 2 was employed in an electrolysis process using anelectrolysis system as depicted in FIG. 3. The anode 28 used was anichrome wire. The electrolyte 38 was an aqueous sulphuric acid solutionhaving a pH of 2. Cathode 2 and anode 28 were held in place in syringebarrel 24 using a cork having holes formed therethrough to allow freemovement of the electrolyte solution. The power source was linked to thecathode by means of an insulated copper wire soldered to the end of thecathode. The light source 34 employed in the test was an AmericanOptical #655 lamp. The system 20 was tested with the light source 34both on and off and using red, green, and blue dicroic additive filters.The system was also tested at various voltage differentials and with noinput provided from the external power source. In each test, the syringe34 was partially filled with electrolyte solution in the mannerdescribed above and the volume of solution in the syringe was recorded.The system was then operated for five minutes and the amount of hydrogenand oxygen gas generated in the test was determined by comparing thefluid volume in the syringe after the test to the fluid volume at thebeginning of the test.

[0051] In these tests, no gas evolution was observed until the lightsource was turned on. The instant inventors also observed that lowervoltages were required to produce electrolysis when the light was “ON”than under similar conditions when it was “OFF”.

[0052] We believe that the observed increase in efficiency is related tothe photoelectric effect as described by Albert Einstein where theenergy of an electron emitted by a metal when struck by a photon oflight is described by the equation:

E=hv−w

[0053] where E is the energy of the electron, h is Planck's constant, vis the frequency of the incident light, and w is the work function ofthe metal. In general, the photoelectric effect is described usingultraviolet light which is of higher energy than visible light. Visiblelight generally does not have sufficient energy to give to an electronto enable it to reduce a hydrogen ion in solution to hydrogen gas.However, this limitation is overcome for purposes of the instantinvention by creating an electrical potential between the anode andcathode.

[0054] The application of an electrical potential to the electrodemodifies the previous equation to read as follows:

E=hv−w+P

[0055] where P is the energy associated with the externally imposedelectric field.

[0056] Essentially, according to our theory of operation, photon energyis used to boost the energy of an electron from the cathode up to theenergy level needed for electrolysis. From this it follows that thewavelength of light required to generate photolysis is related to theexternal electric field. As the field strength (voltage) increases, theminimum energy of photons needed to generate electrolysis drops into thevisible range. With no external electrical field, only photons with highenergy relative to visible light give the electrons enough energy tosplit water into its component hydrogen and oxygen. As the externalelectric potential increases, the minimum energy of a photon needed tosplit water drops into the visible spectrum, and potentially lower.

[0057] This is graphically depicted in Table 1. As illustrated in Table1, the external potential on the electrodes provides the electron energyto go from A (energy level with no applied electric potential) to B(energy level with electric potential applied) but the electron does nothave the energy to electrolyze water until that energy is provided bythe photon of light. In other words, the energy A-C is the total neededfor electrolysis, the energy A-B is provided by the externally imposedpotential on the electrodes, and the energy B-C is provided by the lightphotons. The energy level B varies, increasing with increased imposedexternal potential. As the potential is raised, the additional photonenergy required for electrolysis is reduced, enabling the capture anduse of a larger portion of the incident light. TABLE 1

[0058] Since, according to the photoelectric effect, a photon impartsenergy to a single electron, the number of photons needed of above theminimum energy level is (within limits imposed by the cell design)directly proportional to the number of electrons produced and the amountof hydrogen and oxygen produced. In other words, the more intense thelight, the more hydrogen will be produced, all other things being equal.However, the production of hydrogen can also be limited by the number ofelectrons available at the cathode, or the flow of electrons, or theelectrical current.

[0059] In contrast to other systems heretofore contemplated, it ispreferred that neither the cathode nor the anode employed in theinventive electrolysis apparatus include any semiconductor materials.The inventive apparatus will operate at voltages lower than 2.0,although such operation may be a less efficient use of the photoenergy.Additionally, in the instant invention, it is not necessary (but may bedesirable) to add resistance to the circuit formed by the cathode andanode, other than the resistance that naturally occurs in the cell.Further, the instant invention uses light to energize the electrons inthe cathode metal, rather than to ionize the electrolyte solution. Theinventive system preferably uses the cathode to capture light and act asa surface for electrolysis.

[0060] While the inventive device has been described and illustratedherein by reference to certain preferred embodiments in relation to thedrawings attached hereto, various changes and further modifications,apart from those shown or suggested herein, may be made therein by thoseskilled in the art, without departing from the spirit of the inventiveconcept, the scope of which is to be determined by the following claims.

What is claimed is:
 1. An apparatus for photoelectrolysis comprising: acontainer; a cathode positioned in said container; and an anodepositioned in said container, said container being operable to allowtransmission of light to said cathode from a light source external tosaid container and said cathode comprising a base of conductive metalblacked with a layer of conductive metal in a manner such that saidlayer of conductive metal is operable for both absorbing said light andfor acting as a cathodic surface for electrolysis.
 2. The apparatus ofclaim 1 wherein said base has been blacked by electroplating a surfaceof said base to form said layer of conductive metal thereon.
 3. Theapparatus of claim 1 wherein said base is a sheet of conductive metal.4. The apparatus of claim 3 wherein said layer of conductive metal isdeposited on one side of said sheet of conductive metal.
 5. Theapparatus of claim 4 wherein said anode is an array of rods positionedadjacent said layer of conductive metal.
 6. The apparatus of claim 3wherein said base is formed in a shape of a partial cylinder having aninside surface and wherein said inside surface has been blacked withsaid layer of conductive metal.
 7. The apparatus of claim 6 wherein saidanode is an elongate member positioned adjacent said inside surface suchthat all points of said inside surface are substantially equidistantfrom said anode.
 8. The apparatus of claim 1 wherein said cathodecomprises substantially no semiconductor materials.
 9. The apparatus ofclaim 8 wherein said anode comprises substantially no semiconductormaterials.
 10. The apparatus of claim 1 wherein said cathode consistsessentially of only said base and said layer of conductive metal. 11.The apparatus of claim 1 wherein said base consists essentially of ametal, in elemental form, selected from the group consisting of: copper,nickel, tin, silver, gold, platinum, palladium, graphite, graphitecarbon, iron, chromium, manganese, titanium, and alloys thereof.
 12. Theapparatus of claim 11 wherein said base is formed of copper.
 13. Theapparatus of claim 1 wherein said layer of conductive metal consistsessentially of a metal in elemental form, selected from the groupconsisting of nickel, platinum, palladium, and cobalt.
 14. The apparatusof claim 13 wherein said layer of conductive metal is formed of nickel.15. An apparatus for photoelectrolysis comprising: a container; acathode positioned in said container; and an anode positioned in saidcontainer, said container being operable to allow transmission of lightto said cathode from a light source external to said container, and saidcathode being substantially free of any semiconductor materials andcomprising a base of conductive material blacked with a layer ofconductive material such that said layer of conductive material isoperable for both absorbing said light and for acting as a cathodicsurface for electrolysis.
 16. The apparatus of claim 15 wherein saidcathode consists essentially of only said base and said layer ofconductive material.
 17. A method for producing hydrogen by electrolysiscomprising: (a) placing an electrolyte in a cell including an anodepositioned in said electrolyte and a cathode positioned in saidelectrolyte, said cathode being substantially free of any semiconductormaterials and said cathode comprising a base of conductive materialblacked with a layer of conductive material in a manner such that saidlayer of conductive material is operable for both absorbing light andacting as a cathodic surface; (b) exposing said layer of conductivematerial to a light source; and (c) establishing an electrical potentialbetween said anode and said cathode using an external electrical powersource.
 18. The method of claim 17 wherein said electrolyte is an acidicsolution.
 19. The method of claim 17 wherein said layer of conductivematerial consists essentially of a metal selected from the groupconsisting of nickel, platinum, palladium, and cobalt.
 20. The method ofclaim 19 wherein said base has been blacked with said layer ofconductive material by electroplating.